Electrospray ionisation tandem mass spectrometry in the characterisation of isomeric benzofurocoumarins

A set of aminoalkoxy-substituted, differently annullated furocoumarins, differing in the position of the aminoalkoxy chain and in the unsaturation level of the fused ring, has been subjected to electron impact and electrospray ionisation (ESI) experiments. In order to achieve a distinct characterisation of isomeric compounds, which partially failed under electron impact conditions, collision-induced dissociation experiments were performed on protonated molecules. The breakdown curves obtained by varying the tickle voltage on an ion trap ESI instrument led to the desired characterisation.